It was the middle of summer when Lena first entered the Museum of Dreams. The building resembled an old abandoned cathedral, and the huge doors creaked shrillly at every touch. She had the impression that the walls were breathing - once cold and rough, once smooth as silk. The invitation she received in the mail had no sender. It showed only a golden key and a short sentence: "Come if you can dream." As she crossed the threshold, she felt the taste of morning dew on her tongue and heard the quiet murmur of conversation, although the corridor was empty. The twilight was illuminated only by candles hovering just above the floor. They guided her, swirling among the shadows. She stopped at a large door with a sign engraved "Phantasmagoria". She opened it without hesitation. The hall was filled with glass showcases in which colourful mists swirled instead of exhibits. In one she saw herself on top of a high mountain, in another, flying above an endless sea. Each display case showed fragments of the dreams of those who had once been here. Hovering over everything was the figure of the Museum Director - a tall woman with silver hair and eyes full of endless stories. - 'Everyone who enters here leaves a trail of dreams behind them,' she said quietly, and Lena felt she couldn't answer. - Tonight is a special night. A certain exhibition is changing faster than it should. Come, I'll show you something unusual. They walked through chamber after chamber, passing portraits of dreaming children, magic mirrors and maps of unknown worlds. Finally, they stopped in front of a door bearing a seal with the letter 'M'. - 'Only once every hundred years does someone open it,' whispered the Headmistress. - If you are ready, you can enter. Lena felt her heartbeat quicken. She looked at the key she still held in her hand. Would she dare to cross the threshold? What hides behind a door that no one has opened for a century?